Backing-plate-driven cyclic rolling mill

ABSTRACT

A cyclic operating rolling mill wherein one or more working rolls of small diameter, operating on one or both sides of the workpiece, are disposed between the workpiece and rigid housing beams, and are reciprocated along an inclined path by means of a drive plate to produce the reduction. The drive plate drives the work rolls by frictional contact along the same generator which transmits the roll-separating force to said rigid-housing beams. The workpiece is independently fed into the mill, and means are provided to obviate a scalloped condition of the finished workpiece. With a plurality of work rolls a rotation thereof of less than 180* creates an overlap in the rolling paths of the work rolls so that the portions of the work rolls which never contact the driving plate may be given a desired configuration other than cylindrical.

United States Patent Sendzimir [54] BACKING-PLATE-DRIVEN CYCLIC ROLLING MILL [72] Inventor: Tadeusz Sendzimir, c/o T. Sendzimir, lnc.

PO. Box 1350, Waterbury, Conn. 06720 122] Filed: Sept. 18, 1969 121! App]. Nu: 859,154

3,505,849 4/1970 Grube ..72/215 [1s] am nes [451 Jan. 18, 1972 FORElGN PATENTS OR APPLlCATlONS 758,050 9/1956 Great Britain ..72/2l4 Primary Examiner- Lowell A. Larson Atlarney-Melville, Strasser, Foster & Hoffman 5 7] ABSTRACT A cyclic operating rolling mill wherein one or more working rolls of small diameter, operating on one or both sides of the workpiece, are disposed between the workpiece and rigid housing beams, and are reciprocated along an inclined path by means of a drive plate to produce the reduction. The drive plate drives the work rolls by frictional contact along the same generator which transmits the roll-separating force to said rigid-housing beams. The workpiece is independently fed into the mill, and means are provided to obviate a scalloped condition of the finished workpiece. With a plurality of work rolls a rotation thereof of less than 180 creates an overlap in the rolling paths of the work rolls so that the portions of the work rolls which never contact the driving plate may be given a desired configuration other than cylindrical.

" INVENTOR TADEUSZ SENDZIMIR MELWLLE. sTRAsseR. TE a 3 HOFFMAN Foe R ATTORNEYS PATENTEDJANINR 3,635,065

SHEET 2 UF 2 INVENTOR 52a TADEUSZ SENDZIMIR STLASSBR FOSTER 0nd ATTORNEYS BACKING-PLATE-DRIVEN CYCLIC ROLLING MILL BRIEF SUMMARY OF THE INVENTION The invention has to do with a cyclic-operating rolling mill for single pass reduction of slabs of great width to strip thickness.

In the production of sheets of special metals, for example metals having a high resistance to corrosion, high strength at elevated temperatures, or other special characteristics, investment in a conventional multistand hot strip mill is not justified because the quantities to be produced are relatively small. Furthermore, conventional mills are not adaptable to the temperature and reduction cycles required for these special metals.

Among such requirements 7 is the rolling thereof at moderately low temperatures which will leave the metal in a work-hardened condition but where the work-hardening is less severe than it would be if the reduction had been performed cold. Another such requirement is a short cycle of plastic reduction rather than a series of pass reductions to reach final gauge. Yet another requirement is the maintenance of a uniform temperature during the entire period of plastic reduction.

The above-noted requirements and many others are met in a cyclic mill where the entire zone of plastic reduction (roll bite) is hardly more than about five times the thickness of the slab. In known mills of the cyclic type, either the width of the slab is strictly limited or the mill mechanisms are so complex that they cannot operate at elevated temperature without excessive maintenance.

The mill of the present invention overcomes the width limitation by using rigid beams of the mill-housing parallel to the'work rolls as the final backing elements. The work rolls may therefore be of small diameter which is mandatory for the reduction of such refractory alloys.

According to the present invention one or more work rolls is provided on one or both sides of the slab to be reduced and the work rolls are disposed between the slab and the rigid housing beams which back them over their entire length and the work roll or rolls are caused to reciprocate in a rolling path at an angle to the pass line by means of a drive plate, the working rolls being also backed throughout their entire extent of their rolling path.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a mill according to the present invention having two-upper and two-lower working rolls, the view being taken on the line 11 of FIG. 2.

FIG. 2 is a cross-sectional view of the same taken on the line 2-2 of FIG. I.

FIG. 3 is a plan view thereof.

FIG. 4 is a horizontal cross-sectional view taken on the line 4-4 of FIG. I. 7

FIG. 5 is a schematic vertical cross-sectional view of the end portion of the roll bite according to one embodiment of the invention.

FIG. 6 is a similar schematic cross-sectional view of another embodiment of the invention.

FIG. 7 is an enlarged detailed view of the embodiment of FIG. 6.

FIG. 8 is a schematic cross-sectional view of the embodiment of FIGS. 6 and 7 taken through the neck of a roll.

FIG. 9 is a partial cross-sectional view taken on the line 9- 9 of FIG. 8.

FIG. 10 is an elevational view with parts in cross section of a roll including an edging configuration.

FIG. ll is a vertical cross-sectional view through the roll of FIG. I0; and

FIG. 12 is a somewhat diagrammatic view of a roll showing another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION Referring particularly to FIG. I, the rigid beams of the housing are indicated at I and 1a. The entering slab is indicated at S and the finished strip is indicated at S. In this embodiment by way of example, a structure with two-working rolls on each side of the slab has been illustrated. The work rolls of the upper pair are indicated at 2 and 3 and the corresponding lower pair at 2 and 3. These rolls are journaled in guide plates 5 and 5 respectively, and the work rolls are caused to reciprocate by means of an intermediate or drive plate 4. The drive plate 4 bears against the bearing plate 14 which may be a separate plate, or if desired it may be integral with the housing beam. The bearing surfaces of the plates 14 are disposed at a converging angle in the pass line whereby as the drive plates 4 and 4' are moved to the right, the rolls 2 and 3 and the rolls 2 and 3 are caused to approach each other to produce the reduction. The drive plates 4 and 4' drive the respective work rolls 2, 3 and 2, 3' by frictional contact. Means are provided as will hereinafter be described, to reciprocate the drive plate and also to reciprocate the guide plate. It will be understood that the drive plate must move twice as fast and twice the distance of the guide plate because of the rolling contact between the drive plate and the work rolls. While a mill according to the present invention may have a single work roll on each side of the slab, it is preferable to provide two or more. The preference for at least two work rolls arises from the fact that by dividing the work between two pairs of rolls, the same reduction may be accomplished with one-half the stroke of the drive plate which would be required with a single pair of work rolls. Thus, the number of strokes per minute permissible is substantially increased.

It will be clear that the driving plate 4 is not subject to bending moments and the result of roll pressure since the beam 1 against which it bears is much more rigid than the plate. As a result, the driving plate may be made fairly thin whereby its inertia is reduced so as to permit of rapid reciprocation resulting in higher production of the mill.

The bearing plates 14 provide an angle for the roll path to penetrate into the slab. This angularity is determined by the tolerance of the particular material being rolled. If both faces of the drive plate 4 are flat and parallel, the work rolls during their working stroke will travel along a straight line entering the roll bite at an angle determined by the bearing plate 14 and continuing in this straight line until the end of the stroke, at which point the distance between the rolls 3 and 3' determines the thickness of the finished strip. Without more, the surface of the finished strip would not be fiat but would exhibit a series of roll imprints or scallops.

In order to produce flat or unscalloped strip, the driving face of the drive plate 4 is provided with a profile which makes engagement and disengagement of the work roll with the workpiece more gradual and causes the roll face to contact the slab almost parallel with its surface and then to proceed down the roll bite at the selective angle and then return to parallel before leaving contact with the finished strip. This profile will produce a strip without surface irregularities or scallops. As seen in FIG. 5, when the work roll 3 contacts part a of the profile, the work roll is caused to move parallel with the face of the strip S and thus produces a smooth surface. The portion b of the profile is a deeper relief which permits the work roll 3 to become disengaged from the workpiece.

As pointed out above, the basic principles of the invention are valid for a single pair of work rolls as, for example, 3 and 3. They are also valid for a single work roll on only one face of the slab with the other face bearing upon an anvil or the like indicated at 17 in FIGS. 5 and 6. However, for most purposes it will be preferred to provide working rolls on both sides of the workpiece and to provide more than one pair.

The reciprocation of the drive plates is accomplished by means of a prime mover II which through appropriate gearing drives the two-symmetrical cranks I0 which are connected to levers 8, which are keyed to the shafts 9 so as to oscillate them in counterrotation. Gear segments 7 are keyed to the shafts 9 and these gear segments mesh with racks at both ends of the drive plates 4 and 4'. (See lower portion of FIG. 4.) The shafts 9 also have keyed to them the gear segments 12 which similarly mesh with racks at the ends of the guide plates and 5' (see upper portion of FIG. 4.) It will be understood that the segments 12 and their associated racks have pitch diameters one-half those of the segments 7 and their associated racks, whereby to cause the stroke of the guide plates 5 and 5' to be one-half that of the drive plates 4 and 4'.

As best seen in FIG. 4, a pair of line-edging rolls 6 are mounted on vertical axes in the opposed guide plates 5 and 5 (see also FIGS. 1 and 2.)

Since it is sometimes necessary in conventional mills to contour the working rolls in order to produce a flat strip, provision is made for achieving a flat strip with the present mill. However, instead of contouring the rolls (which cannot be done because they must be completely backed throughout their length), the pressure bearing area of the beams l and 1a for the bearing plates 14 affixed thereto are subdivided into a plurality of bearing areas transversely of the mill. By controlling the lubricant pressure in each area individually the roll pressures transversely of the slab can be varied as necessary in order to produce a flat sheet. This is illustrated in FIGS. 1 and 2 where it will be seen that the lubricant pockets 71 transversely of the mill are separate (four are shown in the Figure but it will be understood that more may be provided if desired), and separate passages for the lubricant to the individual pocket 71 are provided at 72.

Since the cyclic action of the work rolls would push the slab back and thus not produce a reduction, it is necessary that the slab S be advanced by suitable feeding means such as the rolls 13 suitably driven from an outside power source. A suitable rate of feed is between one-half percent and 2 percent of the work roll diameter. Thus, for example, if the work rolls have a diameter of 4' inches, the feed of the slab should be about 0.050 inch per stroke.

During the return stroke of the work rolls, it is preferable to lift them free of contact with the workpiece and to let them continue to rotate by inertia until the next cycle begins. This may be accomplished, for example, by moving one or both of the bearing plates 14 against which the drive plates 4 bear up and down as, for example, by means of a wedge 15 which is reciprocated parallel to the pass line by means of a pair of rods 16, one at each end of the wedge. These rods may be actuated by any suitable linkage (not shown). The rods 16 actuate the wedge to free the work rolls at the end of each stroke and to return them to their working position before the beginning of the next stroke. The wedge mechanism described also serves as a mill screw down since the position of the wedge 15 determines the position of the bearing plate 4 which in turn determines the distance between the finishing work rolls 3 and 3' at the end of the working cycle. It will also be understood that means (not shown) are provided for individual adjustment of the rods 16 to insure parallelism of the work rolls.

Turning now to the embodiment of FIGS. 6 to 9, there is shown an embodiment where a larger number of work rolls is employed. In this particular embodiment, all of the working rolls are disposed on one side of the slab; but it will be clear that the structure of FIG. 6 can be reproduced for the other side of the slab. In these Figures, there are shown two intermediate drive plates 51 and 51' which are oscillated toward and away from each other by means (not shown) but which may be the same as those described heretofore. In this embodiment, each of the plates 51 and 51' drives four work rolls shown, respectively, at 52 and 52'. These work rolls are disposed very close to each other with a minimum clearance between them. Thus, in order to produce a pass reduction equivalent to a pass of a single work roll oscillating over the entire length of the roll bite, each of the work rolls 52 and 52 needs only to travel a distance equal to its diameter. This results in a reduction of the momentum of the reciprocating masses and permits an increase in the number of strokes per minute. Furthermore, the division of the full stroke (and the stroke may be divided into a greater or lesser number of segments depending on the proportions of the mill and the rolling program) also results in a reduction in the maximum angular velocity of the rolls. Therefore, it is no longer necessary to lift the backing plate at the end of each working stroke so as to let the work rolls spin freely during the return stroke which is an idling period. With this embodiment, the work rolls may remain in working contact with the slab during the return stroke as well, which means that their rotation is reversed while under rolling pressure. Because of the relatively slow angular velocity of the work rolls in this embodiment, this reversal is not objectionable and is far outweighed by the gain in achieving two-working strokes for each complete cycle instead of one.

In the detailed view of FIG. 7, it will be observed that the backing plate 51 has a relief 53 in the middle of the stroke and this relief is necessary to permit the roll 52 to jump back to its correct geometric position along the roll bite, from which position the precessional movement has displaced it. The locating bearings on the guide plates permit the roll necks freedom of precession against spring pressure and the spring pressure returns the resmctive rolls to their correct position the moment each roll passes the relief 53 on the drive plate which liberates it from the roll-separating force.

As the roll passes under the relief 53 it is traveling at its maximum speed and as it continues over the remaining portion of the stroke, it decelerates to a stop and immediately reverses and accelerates in the opposite direction. Instead of having the roll 52 transmit its energy of deceleration to the drive plate 51 by frictional contact and to be accelerated in the reverse direction by the same drive plate, means are provided to convert that energy into potential energy of elastic means such as springs. The potential energy is then used to accelerate the roll in the opposite direction during the following stroke. The advantage of such an arrangement is that production may be increased because the number of strokes per minute may be increased since the energy of plastic deformation, i.e., the main drive of the mill, can only be supplied to the roll by frictional contact with the driving plate. The amount of energy so transmitted is limited by the coefficient of friction which for lubricated hard steel rolls is rather low. The arrangement now to be described relieves the main drive of this superposed transmission of energy deceleration and acceleration.

Referring to FIGS. 8 and 9, there is shown an exemplary embodiment of an energy accumulator in the form of coil springs 56, 56' whose inner wrap is snapped on to the torquetransmitting configuration of the neck 52a of the roll 52. As is shown, the outer wrap may exceed the diameter of the roll 52 and the outer end of the coil spring is secured to a cage 54 as by means of pins 57 in a recess or bore 58 which serves precisely to locate the spring 56. It will be understood that a spiral spring of sufficient flexibility to permit oscillations of only about 60 in either direction to produce the required stroke equal to one roll diameter will still be rigid enough to locate the roll when it is set free from roll separation forces by the recess 53 at the middle of the stroke. Thus, the springs 56 (and it will be understood that each work roll is provided with such springs) fulfill the function of torsion accumulators for decelerating and then reaccelerating the rolls at each end of the stroke as well as serving as locating bearings for tying the positions of the rolls to the positions of the drive plate 51 while at the same time allowing the rolls freedom of precession to follow the flow of material.

Since the rolls oscillate only over an arc of 60, it will be clear that portions of the roll face which are in contact at any time with the workpiece never contact the drive plate 51. As a result of this, a number of possibilities become available. The portions of the work rolls which engage the workpiece to produce plastic deformation thereof need no longer by cylindrical as is necessary for those portions which contact the drive plate 51. They may now be shaped or profiled for bestrolling results. Thus, for example, it is possible to reduce the slab 5 gradually with profiled rolls so as first to produce a transverse concave surface and then gradually when approaching final gauge, to go to an even thickness transversely of the strip. By the term gradually it is meant that the succeeding rolls 52 are shaped in their working areas to progressively different profiles.

it is also possible to shape the rolls to restrict lateral spreading of the material of the workpiece which tends to produce side cracks in the finished strip. Such a roll is shown in FIGS. and 11. The face of the roll 52 is cylindrical except for the portion 5211 which protrudes with a neatly rounded filet transition border 52c which engages the edge of the workpiece. The side thrust created by the contact with the edge of the workpiece is taken up by a suitable thrust bearing which is adjustable for various slab widths by such means as a collar 61 secured by a nut 62 and engaging the edge of the drive plate 51. Adjustment for width is obtained by the shims 63.

The opposite edge of the workpiece is engaged by a similar protrusion on the succeeding roll 52 at the other side. it will be understood that such edge working protrusions may be provided on some or all of the work rolls.

Yet another possibility resulting from the limited rotation of the work rolls is in rolling profiles other than flat surfaces. One such example is shown in FIG. 12 which shows a part of an upper roll 52 (the cooperating lower roll will have a complementary configuration.) Such a pair of rolls converging on a workpiece may be used to produce a multiplicity of metal strands (rods or wires). Rolls having profiles such as in FIG. 12 need usually be provided only on the rolls making the last one or more finishing passes, depending upon the shape of the profile it is desired to produce.

It will be understood that the description and the drawings have been by way of example and no limitations other than those set forth in the claims which follow are intended or should be assumed.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A cyclic-rolling mill for rolling a flat workpiece, said mill having a rigid beam housing, at least one small diameter work roll having a rolling path at an angle to the pass line of said workpiece, said work roll being backed over its entire length and along its entire rolling path by said beam housing, a drive plate interposed between said beam housing and work roll, means to reciprocate said drive plate to produce a rotation of said work roll of less than 1 2. A mill according to claim 1, wherein the contact area between said housing beam and said drive plate is a hydrostatic bearing divided into a plurality of areas transversely of said mill, and means for individually controlling the lubricant pressure in said areas in accordance with roll pressures required in said areas, to obtain a flat product.

3. A mill according to claim 1, wherein a plurality of work rolls is disposed over the entire deformation zone of the workpiece, such that a rotation of said work rolls of less than l80 will cause the paths of adjacent work rolls to overlap.

4. A mill according to claim 3, wherein the portions of said work rolls which do not contact the drive plate are profiled, whereby to produce strip having other than a rectangular cross section.

5. A mill according to claim 1, wherein said profile portions include at least one-edging flange.

6. A mill according to claim 4, wherein said profiled portions comprise corrugations parallel to said rolling path, whereby to subdivide the finished workpiece into a plurality of narrow elements.

7. A mill according to claim 1, wherein said roll has a neck, and wherein elastic means is affixed to said neck, said elastic means constituting a torque energy absorber which returns said energy to said neck during the return stroke.

8. A mill according to claim 7, wherein said elastic means are rigid enough to also locate the roll with respect to its cage.

9. A mill according to claim 8, wherein said drive plate is rovided with reliefs, one for each work roll about midway of its travel, in which said elastic means can located it with respect to its cage, as well as return it to its initial angular position.

10. A mill according to claim 4, in which said plurality of work rolls is divided into two groups, each group being reciprocated by one driving plate, and means to reciprocate said plates towards and away from each other. 

1. A cyclic-rolling mill for rolling a flat workpiece, said mill having a rigid beam housing, at least one small diameter work roll having a rolling path at an angle to the pass line of said workpiece, said work roll being backed over its entire length and along its entire rolling path by said beam housing, a drive plate interposed between said beam housing and work roll, means to reciprocate said drive plate to produce a rotation of said work roll of less than 180*.
 2. A mill according to claim 1, wherein the contact area between said housing beam and said drive plate is a hydrostatic bearing divided into a plurality of areas transversely of said mill, and means for individually controlling the lubricant pressure in said areas in accordance with roll pressures required in said areas, to obtain a flat product.
 3. A mill according to claim 1, wherein a plurality of work rolls is disposed over the entire deformation zone of the workpiece, such that a rotation of said work rolls of less than 180* will cause the paths of adjacent work rolls to overlap.
 4. A mill according to claim 3, wherein the portions of said work rolls which do not contact the drive plate are profiled, whereby to produce strip having other than a rectangular cross section.
 5. A mill according to claim 1, wherein said profile portions include at least one-edging flange.
 6. A mill according to claim 4, wherein said profiled portions comprise corrugations parallel to said rolling path, whereby to subdivide the finished workpiece into a plurality of narrow elements.
 7. A mill according to claim 1, wherein said roll has a neck, and wherein elastic means is affixed to said neck, said elastic means constituting a torque energy absorber which returns said energy to said neck during the return stroke.
 8. A mill according to claim 7, wherein said elastic means are rigid enough to also locate the roll with respect to its cage.
 9. A mill according to claim 8, wherein said drive plate is provided with reliefs, one for each work roll about midway of its travel, in which said elastic means can located it with respect to its cage, as well as return it to its initial angular position.
 10. A mill according to claim 4, in which said plurality of work rolls is divided into two groups, each group being reciprocated by one driving plate, and means to reciprocate said plates towards and away from each other. 